Upper Klamath Basin Groundwater Studies

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Since the late 1990s the USGS has worked to characterize the regional groundwater hydrology of the upper Klamath Basin. Research focuses on collecting data to help evaluate the state of the groundwater system and its response to external stresses, and to develop computer models to provide insights useful for water management. These efforts build on earlier USGS studies in the basin going back to the 1950s.

Overview of the Groundwater Hydrology of the Upper Klamath Basin

The upper Klamath Basin has a substantial regional groundwater flow system. The volcanic rocks that underlie the region are generally permeable and compose a system of interconnected aquifers. Interbedded with the volcanic rocks are sedimentary rocks composed of fine-grained lake sediments and basin-filling deposits. These sedimentary deposits have low permeability, are not good aquifers, and probably reduce groundwater movement in some areas. The regional groundwater system is underlain and bounded on the east and west by older volcanic and sedimentary rocks that have generally low permeability.

Overview of the Regional Groundwater Model

The U.S. Geological Survey MODFLOW model simulations show that the timing and location of the effects of groundwater pumping vary markedly depending on pumping location. Pumping from wells close to groundwater discharge features, such as springs, drains, and certain streams, can affect those features within weeks or months of the onset of pumping, and the impacts can be essentially fully manifested in several years. Simulations indicate that seasonal variations in pumping rates are buffered by the groundwater system, and peak impacts are closer to mean annual pumping rates than to instantaneous rates. Thus, pumping effects are, to a large degree, spread out over the entire year. When pumping locations are distant from discharge features, the effects take many years or decades to fully impact those features, and much of the pumped water comes from groundwater storage over a broad geographic area even after two decades. Moreover, because the effects are spread out over a broad area, the impacts to individual features are much smaller than in the case of nearby pumping.

Overview of Groundwater Management Modeling Efforts

A groundwater management model was developed to identify optimal strategies to meet water-user needs while not violating defined constraints on impacts to groundwater levels and streamflows. The overall goal of the modeling effort was to determine the patterns and rates of groundwater pumping that meet the supplemental groundwater demands of the Klamath Reclamation Project. To ensure that groundwater development does not adversely affect groundwater and surface-water resources, the groundwater-management model includes constraints to withdrawal and drawdown. The model indicates that supplemental groundwater pumping can be managed to avoid adverse effects to groundwater discharge that supports critical aquatic habitat.

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In 1992, the USGS began studying possible causes for the change in trophic status of Upper Klamath Lake. Since then research has expanded to include groundwater, geomorphology, streamflow forecasting, and fish ecology.

Stable isotope (??D and ??18O) signatures of three principal groundwater recharge areas in the 21,000-km2 upper Klamath Basin are used to infer recharge sources for aquifers in the interior parts of the basin. Two of the principal recharge areas, the Cascade Range on the western and southern margin of the basin and uplands along the eastern margin...

Since 2001, irrigators in the upper Klamath Basin have increasingly turned to groundwater to compensate for reductions in surface-water allocation caused by shifts from irrigation use to instream flows for Endangered Species Act listed fishes. The largest increase in groundwater pumping has been in and around the Bureau of Reclamation’s...

The water resources of the upper Klamath Basin, in southern Oregon and northern California, are managed to achieve various complex and interconnected purposes. Since 2001, irrigators in the Bureau of Reclamation Klamath Irrigation Project (Project) have been required to limit surface-water diversions to protect habitat for endangered freshwater...

The upper Klamath Basin encompasses about 8,000 square miles, extending from the Cascade Range east to the Basin and Range geologic province in south-central Oregon and northern California. The geography of the basin is dominated by forested volcanic uplands separated by broad interior basins. Most of the interior basins once held broad shallow...

The upper Klamath Basin spans the California-Oregon border from the flank of the Cascade Range eastward to the Basin and Range Province, and encompasses the Klamath River drainage basin above Iron Gate Dam. Most of the basin is semiarid, but the Cascade Range and uplands in the interior and eastern parts of the basin receive on average more than...

This web page provides access to current and historic groundwater-level data collected by monitoring partners, as well as water-level graphs and maps showing net water-level changes between any two time periods. Data for individual wells are filtered to remove measurements taken during active pumping because they do not accurately represent conditions in the aquifer.

PORTLAND, Ore. — The United States Geological Survey, in cooperation with several Klamath Basin stakeholders, has developed hydrologic datasets for the upper Klamath Basin of south-central Oregon that can help water managers identify and prioritize water uses that could be voluntarily set aside and reallocated to yield an additional 30,000 acre feet of water to Upper Klamath Lake.

Groundwater discharging to streams through springs and seeps is a major source of streamflow in the upper Klamath Basin, helping to sustain flow during the dry months of late summer and fall, according to a report recently released by the U.S. Geological Survey (USGS) in cooperation with the Oregon Water Resources Department.